Game Asset texturing; high poly to low poly
In case someone else is struggling with the same issue (Cycles Render):
Presets:

Make a UV of the low poly
Make a UV of the high poly (Smart UV Project did a wonderful job)
Make a new material for both objects.
Make a new image in the UV/Image editor for both objects
Add an Image Texture in the Node editor for both objects, with their own images (those made in the previous step) assigned to them. If you can't add nodes, tick the Use Nodes box
High poly object was painted in the Texture Paint mode, Display mode/Viewport shading set to Texture. Face selection masking was enabled, in order to paint specific faces. Brush set to Fill
Hit Image &gt; Save Image once in a while in the UV/Image editor so not to lose hours of work. (It did this to me a few times.)

The baking:

Go to Render &gt; Bake, like you would when doing normal maps.

Set Bake Type to Diffuse and then uncheck Direct and Indirect, leaving only Color toggled on. (Because if there are no lamps in the scene, the result will be dark)

Remember to tick the Selected to Active box.

Select both objects, the high poly first, the low poly last. Making the former the Selected and the latter the Active

Make sure both objects are occupying the same coordinates / are in the exact same place.

Hit Bake and wait.


Like I said in the original post: I'm very new to this, but these steps got me the results I wanted, or at least I can use it.
Here's a pic just for good measure, don't mind the ugly colors, those were just for the proof of concept.


And here it is in Unity almost finished